According to the results of the study, the closure of a narrow waterway between Russia and Alaska can help stabilize a vulnerable ocean current system.
The Bering Strait in summer. Photo: NASA
The satellite image shows a narrow strait with dark blue water separating two green landmasses facing each other.
Cloud lightening. Freezing of the Arctic. A giant umbrella in outer space. Dutch scientists have added another one to the list of crazy ideas to combat climate change: to build an 80—kilometer-long dam across the Bering Strait, a shallow stretch separating Russia and Alaska.
In a study published Friday in the journal Science Advances, scientists show that under certain conditions, such a dam can prevent the destruction of an ocean current system known as the Atlantic Meridional Tipping Circulation, which plays a key role in regulating Earth’s climate.
In recent decades, the North Atlantic circulation has weakened, and there is increasing evidence that human-induced warming may lead to its complete cessation or significant slowdown, which will seriously affect the weather on many continents.
It transports warm salty waters from the tropical Atlantic Ocean past the Eastern coast towards Europe. There, the water gives off its heat to the air and helps to soften the climate in the UK and the Nordic countries. At the same time, the water cools, sinks to the bottom and returns to the south, where it affects the precipitation regime in Africa, South America and other regions.
However, now the warming caused by greenhouse gases in the atmosphere is disrupting the operation of this huge oceanic conveyor belt. As temperatures rise, there is more precipitation in the Arctic, and the Greenland ice sheet is melting, which is why more fresh water enters the North Atlantic, which reduces the salinity of its surface.
Because of this, the water in the North Atlantic Meridional Tipping Circulation does not sink at the northern end of the loop, which in turn leads to less warm water coming from the tropics.
Due to the decrease in the amount of water moving north across the Atlantic Ocean, its volume on the east coast of the United States will increase, which will lead to sea level rise. The nature of tropical precipitation will change: it will become drier in some regions, and wetter in others.
At first glance, the role of the Bering Strait in all this is not obvious. In fact, the strait is a gateway through which a large amount of fresh water flows from the Pacific Ocean to the Arctic Ocean, and from there to the Atlantic Ocean. The construction of the dam will change the balance of fresh and salt water between the three oceans.
Scientists have found that if the North Atlantic Oscillation is strong, then closing the strait will lead to a decrease in the influx of fresh water from the Arctic Ocean to the Atlantic Ocean. This will help preserve the salinity of the North Atlantic and the stability of the North Atlantic oscillation. But if the North Atlantic Oscillation is already close to collapse, then closing the strait will have the opposite effect.
According to Thomas Hein, a professor of Earth and planetary sciences at Johns Hopkins University, the study’s conclusions are too vague, and the potential impacts of the dam on fisheries and shipping are too serious. “I think there are a lot of reasons why this would be a very bad idea,” Dr. Hein said.
By Raymond Zhong Source Published with abbreviations
